The Strongest Indoor Pulsed Magnetic Field Ever Generated

They were able to generate a magnetic field of 1200 Tesla using electromagnetic flux compression.

To measure the field strength, they used a reflection-type Faraday rotation probe.

Magnetic fields are extremely important for research in fields of solid state physics like superconductors, semiconductors, strongly correlated electron materials, and various other nanomaterials. Ultra-high magnetic fields (over 1000 Tesla) offer new insights into material science and help us better understand novel physical concepts.

So far, numerous techniques have been developed to generate strong magnetic fields. Mostly, two of them are used to compress the magnetic flux and produce megagauss magnetic fields. The first one is based on explosively-driven flux compression that uses chemical explosive, while the second method is based on electromagnetic flux compression that uses electromagnetic forces generated by powerful condenser bank modules.

Recently, physicists at the University of Tokyo generated the strongest pulsed magnetic field in their lab. Compared to previously generated fields of similar power-levels, this one was preserved for a longer time. The study could have useful applications in fusion power generation and may lead to the development of effective investigative equipment for material scientists.

How Did They Do It?

Physicists developed a sophisticated setup capable of generating ultra-high controllable magnetic field using electromagnetic flux compression. They were able to generate a magnetic field of 1200 Tesla, which is way stronger than any stable artificial field ever produced.

The figure (1200 Tesla) represents a notable milestone. To put this into context, the magnetic field of Earth (measured on surface) ranges from 25 to 65 microteslas. Whereas, the newly developed megagauss generator produces 20 to 50 million times stronger field.

Megagauss generator system | Courtesy of researchers

We saw an exceptional case in 2001 when Russian researchers generated a field of 2800 Tesla, but their explosive technique blew up every instrument involved in the experiment and the field couldn’t be controlled. One can also use lasers to produce extremely strong magnetic field, but they only last for nanoseconds.

The field created in this experiment lasts for nearly 100 microseconds, which is thousands of times longer than laser-generated fields. It is possible to generate long-lasting magnetic fields but then you have to compromise with the strength (reduces to hundreds of Tesla).

How Did They Measure The Magnetic Field?

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A reflection-type Faraday rotation probe was used to measure the magnetic field. They flashed a laser into the center of the liner. The magnetic field rotates the polarization of the laser light, and the degree of the rotation or polarization is analyzed to calculate the strength of the field. This technique is known as Faraday rotation.

Such ultra-high magnetic fields open up intriguing possibilities, for instance, electrons’ motion outside the material environments can be observed. This helps scientists study different types of electronic devices in a whole new light. Moreover, it could push the development of fusion power generation, one of the most promising ways to provide clean energy in the future.